Private Sub CheckTime()
        Dim dayOfWeek As DayOfWeek = us.Calendar.GetDayOfWeek(Date.Today)   ' 
        ' Dagens nummer eks. 3
        Dim d As String = us.DateTimeFormat.GetDayName(dayOfWeek)           ' 
        ' Det engelske navn for dagen eks. Wednesday
        'Dim t As String = Now.ToShortTimeString                             ' _
          Tid f.eks. 17.30
        Dim tsStart As TimeSpan
        Dim tsEnd As TimeSpan
        Dim count As Integer = 0
 
        actOnMotion = False
 
        For Each itm As String In lstOnTimes
            If itm.Contains(d) Then count += 1
        Next
 
        For i = 0 To lstOnTimes.Count - 1
            Dim sStr As String() = lstOnTimes(i).ToString.Split("-")
            If sStr(0) = d Then
                If i = 0 Then tsEnd = TimeSpan.Parse(sStr(1))   ' Listen vender 
                ' modsat derfor tsEnd = id 0
                If i = count Then tsStart = TimeSpan.Parse(sStr(1))
                If DateTime.Now.TimeOfDay >= tsStart AndAlso _
                  DateTime.Now.TimeOfDay <= tsEnd Then
                    actOnMotion = True
                End If
            End If
        Next
 
        Debug.Print(actOnMotion)
    End Sub

    Private Sub AddOnTimes()
        Dim selectedCellCount As Integer =
            dgvMotionPeriode.GetCellCount(DataGridViewElementStates.Selected)
 
        If selectedCellCount > 0 Then
            lstOnTimesInt.Clear()
 
            For i = 0 To selectedCellCount - 1
                Dim col As Integer = dgvMotionPeriode.SelectedCells( _
                  i).ColumnIndex
                Dim row As Integer = dgvMotionPeriode.SelectedCells(i).RowIndex
                Dim cTemp As Integer = col * 10
                Dim id As Integer
                If row < 10 Then id = cTemp & row
                If row > 9 Then id = cTemp / 10 & row
                lstOnTimesInt.Add(id)
            Next i
            CalcOnTimes()
        End If
    End Sub
 
    Public Sub CalcOnTimes()
        lstOnTimes.Clear()
 
        For Each itm In lstOnTimesInt
            Dim row As String = itm.ToString.Substring(1, 2)
 
            Select Case itm.ToString.Substring(0, 1)
                Case 1
                    lstOnTimes.Add("Monday" & "-" & lstTimes(row))
 
                Case 2
                    lstOnTimes.Add("Tuesday" & "-" & lstTimes(row))
 
                Case 3
                    lstOnTimes.Add("Wednesday" & "-" & lstTimes(row))
 
                Case 4
                    lstOnTimes.Add("Thursday" & "-" & lstTimes(row))
 
                Case 5
                    lstOnTimes.Add("Friday" & "-" & lstTimes(row))
 
                Case 6
                    lstOnTimes.Add("Saturday" & "-" & lstTimes(row))
 
                Case 7
                    lstOnTimes.Add("Sunday" & "-" & lstTimes(row))
            End Select
        Next
    End Sub

Public Class frmCheckDateTime
 
    'Für die Auswahl der Zeitintervalle
    Dim dt As New DataTable
    Dim bs As New BindingSource
    Dim dgv As New DataGridView With _
        {.Parent = Me, .DataSource = bs, .Width = 300, .ReadOnly = true}
 
    'Controls für Eingabe des zu prüfenden Zeitpunktes
    Dim datepicker As New DateTimePicker With _
      {.Parent = Me, .Left = 320, .Width = 100, _
       .Format = DateTimePickerFormat.Short}
 
    Dim timepicker As New DateTimePicker With _
        {.Parent = Me, .Left = 430, .Width = 100, _
         .Format = DateTimePickerFormat.Time, .ShowUpDown = True}
 
    'Für die Prüfung des Zeitpunktes
    Dim WithEvents btnCheck As New Button With _
        {.Parent = Me, .Left = 320, .Width = 100, .Top = 100, .Text = "Check"}
 
 
    Private Sub frmCheckDateTime_Load(sender As System.Object, _
        e As System.EventArgs) Handles MyBase.Load
 
        Me.Width = 550
        Me.Height = 500
 
        'Liste der wählbaren Zeitintervalle in die Datatable eintragen
        dt.Columns.Add("Weekday", GetType(String))
        dt.Columns.Add("StartTime", GetType(String))
 
        Dim wd As String = GetWeekday(Now)
        For i As Integer = 1 To 7
            Dim wdn As String = _
                DateAndTime.WeekdayName(i, False, FirstDayOfWeek.Monday)
            For hr As Integer = 0 To 23
                dt.Rows.Add(wdn, hr.ToString & ":00")
                dt.Rows.Add(wdn, hr.ToString & ":30")
            Next hr
        Next i
 
        bs.DataSource = dt
    End Sub
 
 
    Private Function GetWeekday(ByVal dtim As DateTime) As String
        Return dtim.ToString("dddd", Globalization.CultureInfo.CurrentCulture)
    End Function
 
 
    Private Function IsIntime(ByVal r As DataRow, dtim As DateTime) As Boolean
 
        'Liegt dtim im Zeitintervall, das in r eingetragen ist ??
        Dim wdn As String = GetWeekday(dtim)
        If Not wdn = r("Weekday").ToString Then Return False
 
        Dim rhour As Integer = CInt(r("StartTime").ToString.Split(":"c)(0))
        Dim rmin As Integer = CInt(r("StartTime").ToString.Split(":"c)(1))
 
        If Not dtim.Hour = rhour Then Return False
        If dtim.Minute < 30 AndAlso rmin = 30 Then Return False
        If dtim.Minute >= 30 AndAlso rmin = 0 Then Return False
        Return True
    End Function
 
 
    Private Function CheckDateTime(ByVal dtim As DateTime) As Boolean
 
        For i As Integer = 0 To bs.Count - 1
            If dgv.Rows(i).Selected Then
                'Ein gewähltes Zeitintervall checken
                If IsIntime(DirectCast(bs(i), DataRowView).Row, dtim) _
                   Then Return True
            End If
        Next i
        Return False
    End Function
 
 
    Private Sub btnCheck_Click(sender As Object, _
        e As System.EventArgs) Handles btnCheck.Click
 
        'Gewähltes Datum und und gewählte Uhrzeit zusammenfügen
        Dim dtim As DateTime = datepicker.Value.Date
        dtim = dtim.AddHours(timepicker.Value.Hour)
        dtim = dtim.AddMinutes(timepicker.Value.Minute)
 
        If CheckDateTime(dtim) Then
            MsgBox("Zeitpunkt liegt in einem gewählten Intervall")
        Else
            MsgBox("Zeitpunkt liegt nicht in einem gewählten Intervall")
        End If
    End Sub
End Class

Public Class frmCheckDateTime2
 
 
    'Für die Auswahl der Zeitintervalle
    Dim dt As New DataTable
    Dim bs As New BindingSource
    Dim WithEvents dgv As New DataGridView With _
        {.Parent = Me, .DataSource = bs, .Width = 700, .Height = 300, .ReadOnly _
        = True}
 
    Dim WithEvents btncheck As New Button With _
        {.Parent = Me, .Top = 350, .Text = "check"}
 
 
    Private Sub frmCheckDateTime2_Load(sender As System.Object, _
        e As System.EventArgs) Handles MyBase.Load
 
        Me.Width = 720
        Me.Height = 400
 
        dt.Columns.Add("StartTime", GetType(String))
 
        For i As Integer = 1 To 7
            Dim wdn As String = _
                DateAndTime.WeekdayName(i, False, FirstDayOfWeek.Monday)
            dt.Columns.Add(wdn)
        Next i
        For hr As Integer = 0 To 23
            dt.Rows.Add(hr.ToString & ":00")
            dt.Rows.Add(hr.ToString & ":30")
        Next hr
 
        bs.DataSource = dt
 
        dgv.MultiSelect = True
        dgv.SelectionMode = DataGridViewSelectionMode.CellSelect
 
        Using g As Graphics = dgv.CreateGraphics
            For i As Integer = 0 To dgv.Columns.Count - 1
                With dgv.Columns(i)
                    Dim sz As SizeF = g.MeasureString(.HeaderText, dgv.Font)
                    .Width = CInt(sz.Width * 1.1)
                    .DefaultCellStyle.SelectionBackColor = Color.Yellow
                    .SortMode = DataGridViewColumnSortMode.NotSortable
                End With
            Next i
         End Using
 
         With dgv.Columns(0).DefaultCellStyle
            .SelectionBackColor = .BackColor
         End With
    End Sub
 
 
    Private Function GetWeekday(ByVal dtim As DateTime) As String
        Return dtim.ToString("dddd", Globalization.CultureInfo.CurrentCulture)
    End Function
 
 
    Private Function CheckTime(ByVal dtim As DateTime) As Boolean
 
        Dim weekday As String = GetWeekday(dtim)
        Dim colindex As Integer = dt.Columns.IndexOf(weekday)
 
        For i As Integer = 0 To dgv.Rows.Count - 1
            If dgv.Rows(i).Cells(colindex).Selected Then
                Dim parts() As String = _
                   dgv.Rows(i).Cells(0).Value.ToString.Split(":"c)
                If CInt(parts(0)) = dtim.Hour Then
                    If CInt(parts(1)) = 0 And dtim.Minute < 30 Then Return True
                    If CInt(parts(1)) = 30 And dtim.Minute >= 30 Then Return True
                End If
            End If
        Next i
        Return False
    End Function
 
 
    Private Sub btncheck_Click(sender As Object, _
        e As System.EventArgs) Handles btncheck.Click
 
        If CheckTime(Now) Then
            MsgBox("Im Intervall")
        End If
    End Sub
End Class